From: Tao Ma <tm@tao.ma>
To: Eric Sandeen <sandeen@redhat.com>
Cc: ext4 development <linux-ext4@vger.kernel.org>,
Theodore Ts'o <tytso@mit.edu>
Subject: Re: Bigalloc ENOSPC woes
Date: Wed, 01 Feb 2012 00:03:09 +0800 [thread overview]
Message-ID: <4F2810BD.6040806@tao.ma> (raw)
In-Reply-To: <4F270949.30800@redhat.com>
On 01/31/2012 05:19 AM, Eric Sandeen wrote:
> I got nervous when I tried this on an -O bigalloc -C 65536 fs:
>
> # echo foo > blah; du -hc blah; sync; du -hc blah
> 4.0K blah
> 4.0K total
> 64K blah
> 64K total
>
> Seems that du should never report less than the cluster size, should it?
It is a bug and the corresponding fix is sent with the subject "ext4:
let getattr report the right blocks in delalloc+bigalloc."
>
> And that made me wonder about ENOSPC handling - are we tracing delalloc allocations correctly?
>
> From running xfstest 204 on a similarly-created fs, it really seems that we are not.
>
> A manual test of creating 4-byte files until ENOSPC (which was really when I ran out of inodes) and then issuing a sync led to a storm of kernel messages about allocation failures:
>
> [ 482.154538] EXT4-fs (sdb6): delayed block allocation failed for inode 1664 at logical offset 0 with max blocks 1 with error -28
> [ 482.154540] EXT4-fs (sdb6): This should not happen!! Data will be lost
>
> <ad infinitum, or at least 600 or so in my case>
>
> and an end result of a bunch of 4 byte long files with no extents. Almost like files full of NULLs. Careful - that is hard to live down. :)
yeah, I can reproduce it easily and more investigation is needed here.
Thanks
Tao
>
> Ted, are you aware of those issues in bigalloc?
>
> -Eric
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prev parent reply other threads:[~2012-01-31 16:03 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-30 21:19 Bigalloc ENOSPC woes Eric Sandeen
2012-01-30 22:31 ` Ted Ts'o
2012-01-31 16:03 ` Tao Ma [this message]
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